Mitochondria are double membrane-bound organelles found in the cytoplasm of nucleated eukaryotic cells. They are found in almost every cell of the human body except red blood cells. They are the cell's primary site of energy metabolism and generate adenosine triphosphate (ATP) for different cell functions. Typically, more than 90% of a cell's requirement for ATP is supplied by the cell's own mitochondria.
Mitochondria are composed of two concentric membranes, which have specialized functions. The inner mitochondrial membrane contains proteins for ATP synthase. The outer mitochondrial membrane, which contains large numbers of integral membrane proteins, encloses the entire organelle.
The structure of mitochondria has striking similarities to some modern prokaryotes. In fact, mitochondria are thought to have originated from an ancient symbiosis when a nucleated cell engulfed an aerobic prokaryote. In the symbiosis relationship, the host cell came to rely on the engulfed prokaryote for energy production, and the prokaryote cell began to rely on the protective environment provided by the host cell.
Due to mitochondria's primary function in cell metabolism, damage and dysfunction in mitochondria can cause a range of human diseases. Diseases caused by mutation in the mitochondrial DNA (mtDNA) include Kearns-Sayre syndrome, MELAS syndrome and Leber's hereditary optic neuropathy. These diseases are often transmitted by a mother to her offspring. Moreover, diseases such as Kearns-Sayre syndrome, Pearson syndrome, and progressive external ophthalmoplegia are thought to be due to large-scale mtDNA rearrangements.
Furthermore, damage and dysfunction in mitochondria can also be caused by acquired mitochondrial conditions. These acquired mitochondrial conditions may be caused by injury, toxicity, chemotherapy, and age-related changes. Particularly, ischemia/reperfusion injury can cause mitochondrial damage, which will have a negative impact on oxygen consumption and energy synthesis.
Currently, there are no known and approved treatments that involve mitochondria. There is a need for such treatment. There is also a need to utilize mitochondria for drug delivery and some other therapeutic and diagnostic purposes.